Generally, a process of forming a resist pattern on a substrate, which is one of manufacturing processes of a semiconductor device or a FPD substrate, is performed by a series of processes of forming a resist film on the substrate, e.g., a semiconductor wafer (hereinafter, referred to as a “wafer”); exposing the resist film through a photomask; and developing the exposed resist film so as to obtain a desired pattern. Conventionally, the series of processes have been performed by a coating and developing apparatus.
In a coating unit for applying, for example, a resist solution serving as a coating solution to a wafer, a cup body is provided so as to surround a spin chuck, which is a substrate holding unit, and processes such as spin coating of the resist solution, spin drying and side-rinse are performed by supplying the resist solution onto a substantially central position of a wafer held on the spin chuck and rotating the spin chuck.
The supply of the resist solution onto the wafer is carried out by pouring the resist solution supplied from a supply unit through a nozzle (coating solution nozzle). Further, the nozzle may be usually in a standby state at a position away from a wafer loading/unloading path so as not to obstruct a loading/unloading operation of the wafer, and only when the resist solution is poured, the nozzle is moved to the center of the wafer held on the spin chuck.
In the coating unit, plural kinds of resist solutions have been used depending on the kind of a base film on which the resist film is formed or a thickness of the resist film. A coating nozzle is provided for each kind of resist solution, and is configured to be moved by a common driving arm between a standby position and a processing position where the coating process of the resist solution is performed. With this configuration, since a coating nozzle needs to be replaced by the driving arm, there is required many operation processes. Further, since a discharge (pouring) position of each nozzle with respect to the substrate needs to be adjusted individually by the driving arm, the process becomes troublesome.
In this regard, there has been known a resist coating apparatus having a configuration in which a plurality of coating units is juxtaposed in a row and coating nozzles are integrated as one body on a common driving arm movable between the plurality of the coating units juxtaposed in the row (see, for example, Patent Document 1).
Conventionally, leading ends of the plurality of coating solution nozzles are in a standby state after performing a suck-back of the resist solution so as to suppress contamination or dryness at an interface between the resist and the atmospheric atmosphere. With respect to the plurality of coating solution nozzles, it is desirable to check a nozzle state of each of coating solution nozzles moved by the driving arm even when they are not used in the coating process, and since these nozzles are moved as one body, there is a need to reduce, for example, a risk of drip of the liquid or a risk of dryness of the liquid. In this regard, it is suggested in Patent Document 1 that an air layer, formed by sealing the leading end of the coating solution nozzle with a liquid, prevents the resist solution from being dried.
With this configuration, conventionally, a dummy dispense of the resist solutions having different dryness levels depending on the kind of the resist solutions or liquids contained therein is set for each resist solution according to the property of each resist. However, by sealing the leading end of the coating solution nozzle with the liquid in the same manner, the resist of the coating solution nozzle is prevented from directly contacting with the external atmosphere, and since the risk of dryness of the coating solution nozzle is reduced, there is no need to perform the dummy dispense for a long time.    Patent Document 1: Japanese Patent Laid-open Publication No. 2006-302934 (see, FIGS. 3, 4 and 8)